Scope.This document is a repair guide for Williams System
11 pinball games made from 1986 (High Speed) to 1990 (Dr.Dude). Some
Bally games from 1988 to 1990 are also included as Williams bought the
Bally pinball name in 1988. Updates of this document are available for
no cost at http://marvin3m.com/fix.htm if
you have Internet access. This document is part three of three
(part one is here, and part two is here). Note the basis
of this document came from the WPC Repair guide. These two
systems are very similar in design.

IMPORTANT: Before Starting!IF YOU HAVE NO EXPERIENCE IN
CIRCUIT BOARD REPAIR, YOU SHOULD NOT TRY AND FIX YOUR OWN PINBALL
GAME! Before you start any pinball circuit board repair, review the
document at http://marvin3m.com/begin, which
goes over the basics of circuit board repair. Since these pinball repair
documents have been available, repair facilities are reporting a
dramatic increase in the number of ruined ("hacked") circuit boards sent
in for repair. Most repair facilities will NOT repair your circuit
board after it has been unsuccessfully repaired ("hacked") by you.

If you aren't up to repairing your circuit boards yourself, I highly
recommend Tom Callahan or
John Robertson (in Canada). Note
these repair facilities will NOT repair your circuit board after it has
been unsuccessfully repaired by you.

Switches on any pinball game are very important. On electronic
games, when a switch closes, it informs the CPU to score points, award
a feature, and/or to activate a solenoid. If a switch is stuck closed,
the CPU will ignore this switch (in most cases).

If a switch is not activated in 30 games, or is permanently closed,
the switch is assumed to be bad. This will create a test report, which
is shown when the game is turned on. If a particular feature of a game
is difficult to score, it's associated switch may be (falsely) assumed
bad (if not activated in 30 games). To correct the test report, remove
the playfield glass, and activate the switch by hand within a game, or
within the diagnostics switch edge test.

All switches on a system 11 game (except for the direct switches at
connector 1J14, which are only the test button switches) are in the
"switch matrix". The switch matrix is controlled by eight switch
columns, and eight switch rows. The cross-section of any row and
column designates any one of the potential 64 different switches. The
switch columns are controlled through CPU board connector 1J8, which
connects to 2N3904 transistors Q42-Q49. The output of these goes to a
74LS244 chip on the CPU board at U40. The output of this chip then
goes to a 6821 PIA at U38. The switch rows are controlled through CPU
board connector 1J10, which connects to 4011 chips at U30 and U39.
This then connects to the same 6821 PIA at U38.

Test Button Switches.On system 11 games, the test button
switches inside the coin door only are wired directly to the CPU board
at connector 1J14. These switches do not go through the switch
matrix on any system 11 revision. The test button switches are direct
switches to the CPU board, which directly to the CPU. The diagnostic
switch connects to the CPU's NMI line. Williams did this so if there
is a switch matrix short, you can still get into the game's diagnostic
tests without using any switches in the switch maxtrix.

Shorting the Switch Matrix to +50 volts.When in a hurry,
many make an under playfield adjustment with the game turned on. Doing
a switch adjustment with the power on could easily short a coil lead
(+25/50 volts) to a switch lead. This will immediately blow the switch
matrix, and fry the most anything to and including the 6821 PIA at
U38. You can bet the switch row 4011 chips at U30 and U39 will have
failed. Also it could take out the switch column 2N3904 transistor(s)
and the 74LS244 chip at U40.

If after replacing the suspect components, disconnect the switch
input plugs from 1J8 and 1J10 at the bottom of the CPU board. Put the
game into switch test mode, and none of the switches should be
activated! If a whole row of switches is activated, that would mean
that something in the row chain is still bad.

Shorting the Flipper EOS switch to the Lane Change
switch.Williams has a feature called "lane change" in many of
their games. This allows the player to change the lit lanes using the
cabinet flipper buttons. Prior to Banzai Run, this is done by doubling
up a second switch on the flipper EOS switches. The EOS switches are a
+50 volt switch. The lane change switch is a +5 logic switch connected
to the switch matrix. These two switches are insulated from each other
by a small nylon "triangle" activator. But if these two switches
touch, the switch matrix will burn (as described above).

Games Cyclone and before: the EOS flipper switch on these
games is actually two switches. The switch on the left (with the diode)
is low-voltage and connected to the switch matrix. This normally open
switch closes when the flipper is activated, and controls the lane
change and high score initials. The switch on the right is the
high-voltage flipper EOS switch. A nylon space insulates the two
switches from each other.

When adjusting or cleaning the flipper EOS switches or lane change
switches, make sure the game is turned OFF. This will prevent shorting
these two switches together. Also, do not clean the smaller lane
change switch with anything other than a business card.

Lane Change on games with Interconnect boards.When the
interconnect board was introduced on Banzai Run, Williams stopped
using a doubled up switch on the flipper EOS switches for the lane
change. Instead, circuitry was added on the interconnect board using a
MOC3010 opto coupler. If you have problems with the lane change on
these games, replacing the small eight pin MOC3010 opto couplers will
usually fix the problem.

Switch Numbering.Each switch has a number associated
with it. Unlike WPC, system 11 switches are just numbered 1 to 64.
There is no relationship to what row or column number the switch
number is (on WPC, switch 43 is column 4 row 3, for example). On
system 11 games, switches 1 to 8 are column 1, rows 1 to 8. Likewise,
switches 9 to 16 are column 2, rows 1 to 8. This continues up to
switches 57 to 64, which are column 8, rows 1 to 8.

To enter diagnostics, the red center button must bein
the "down" position (as shown here). If the centerbutton is "up",
you will enter the audits menu instead.

Using the Internal Switch Tests.To test switches, use
the internal test software. Press the center red button inside the
coin door down, then press the black button closest to the coin door.
Finally, press the center button again. The button closest to the coin
door will take you from test to test. Go to the "switch level" test
and activate any switch on the playfield using a pinball (this
simulates real game play), and it should show on the game's display.

If a Bad Switch is Found.If a switch does not work,
check these things:

On the top side of the playfield, make sure the bad switch
contacts haven't been bashed together by an errant air pinball.

If it's a micro-switch, check the actuator arm. Make sure it's
adjusted properly. Listen for the micro-switch's "click" when
activating. No click usually means the switch is mis-adjusted or
broken.

Check that the wires going to the switch are soldered well, and
haven't fallen off.

Check the continuity (using your DMM's continuity setting) of
the wire between this switch and another working switch in the same
column (white wire) or row (green wire).

If it's a blade or leaf style switch, check the contacts for
proper closure. Clean the switch contacts with a business card (do
NOT use a file as the contacts are gold plated). Put the card
between the contacts, close the contacts, and pull the card through
the contacts. This is all that is needed to clean gold plated switch
contacts.

Check the switch to make sure it works. Use your DMM's
continuity setting, and put one lead on the "common" lug (the lug to
which the banded end of the diode connects) of the switch. Put the
other lead on the green (normally open) switch lug. Your meter
should only beep when the switch is activated, and not beep when the
switch is de-activated. Move the DMM's lead from the green to the
white wire (normally closed) switch lug. Your meter should beep when
the switch is de-activated, and NOT beep when activated.

Check the diode on the switch. Make sure the diode is connected
properly, and is working (see below).

Check other switches in that switch's row or column. Two 4041
chips control rows, and 2N3904 transistors and 74LS244 at U40
control columns. Both rows and columns are controlled by a 6821 PIA
at U38.

If the switch is bad, replace it. If all the switches are bad in a
particular switch column or row, start replacing components closest to
the switch.

System 11 switch matrix of 64 switches: eight rows and
eight columns.

Phantom Switch Closures: a Shorted Switch.It's a
strange problem. You're playing a game, and when the ball goes down
the right inlane, the left slingshot fires! Or when you make a ramp
shot, the game slam tilts. One switch closes, but a completely
unrelated event than occurs.

This is a classic problem of a shorted switch. It confuses the
switch matrix into thinking something else has occurred. This can
happen from an "air" pinball, that bashes an above playfield switch's
contacts together, causing a short. Also a bad switch diode can do
this too. In either case, you need to find the shorted switch.
Unfortunately, it won't be obvious. The switch matrix is confused, so
any diagnostics the game provides will be of limited help.

First, try and find the switch that causes something unrelated
("phantom") to happen. Take the playfield glass off, and start a game.
Activate the switches with your hand, and find the switch which
activates the phantom (unrelated) switch. Once you have found the
switch, go to the game manual and find the switch's number, row
number, and column number. Say for example, switch 53 (column 7, row
5) is causing the phantom closure. Now you need to get the other three
switches that make up the "square" of this row and column. First get
the reverse switch number, switch 39 (column 5, row 7). Then get the
other two switches: switch 37 (column 5, row 5), and switch 55 (column
7, row 7). Your switch short will probably be one of these four
switches.

If you are having problems figuring out if the short is in the
playfield or the CPU board, try this. Remove connectors 1J10 and 1J8
from the CPU board. Then put the game in switch edge test. Using the
manual, find which row and column of the switch that is causing the
phantom closure. Then cross this row and column directly on the CPU
board (with wire and alligator clips, and a diode, as described below
in the "testing the switch columns/rows"). The row and column numbers
for each pin of connectors 1J10 and 1J8 are listed below. If the
phantom switch does not activate, the problem is in the playfield. If
the phantom closure still works, you have a CPU board problem.

If your phantom switch problem is on the CPU board, don't forget to
look at the 1k ohm resistor pack SR10 on the CPU board. When this
resistor pack goes bad, it can cause intermittent phantom switch
closures. Use your ohm meter, and test the resistor pack. If in doubt,
just replace it.

Bad Switch Diode.Each micro-switch on the playfield also
has an 1N4004 diode soldered to it. This diode can short closed. It
doesn't happen often though. Important: If a switch diode does
short closed, all switches in that particular column or row will
exhibit strange behavior. If a switch diode goes permanently open, the
switch will never register. Keep this in mind when diagnosing switch
matrix problems.

Fail-Safe Diode Test.With the game off, use your DMM set
to diode position. With the black lead on the banded side of the
diode, you should get a .4 to .6 volt reading. Reverse the leads, and
get a null reading. If the diode test bad, cut one lead of the diode
from the switch to remove it from the circuit, and test it again just
to make sure the diode is really bad. Reconnect the diode after
testing, or replace it if bad.

Testing a switch diode on a microswitch without removing
thediode. Not the screw driver keeps the switch activated, and
themiddle green wire (ground) has been disconnected.

Testing a Microswitch's Diode, without removal.You can
test the diode on a microswitch without unsoldering a diode lead from
the switch. This technique assumes the switch is wired in the standard
configuration: green (ground) wire to the center lug, the banded end
of the diode to the far switch lug, and the non-banded diode lead and
the switch wire(s) to the close switch lug (as shown in the pictures
above).

Disconnect the middle green (ground) wire from the switch. It
should have a quick connector. If the middle green ground wire is
soldered to the switch, ignore this test and do the above
"fail-safe" diode test.

Put your DMM on diode setting.

Connect the black lead of your DMM to the diode's banded side,
and the red lead to the non-banded side.

Activate the switch.

You should get a reading of .4 to .6 on the meter.

Reverse the DMM's leads (red lead to the diode's banded side),
and keep the switch activated. You should get a null meter reading.

Testing a Blade/Leaf Switch's Diode.Testing the diode on
a leaf switch is far easier. No wires need to be disconnected, and the
switch should not be activated. This technique assumes the switch is
wired in the standard configuration: green (ground) wire to the center
lug, the banded end of the diode solo, and the non-banded diode lead
and the switch wire(s) to the other switch lug (as shown in the
pictures below).

Leave the leaf switch's diode and all wires connected.

Make sure the switch isn't activated.

Put your DMM on diode setting.

Connect the black lead of your DMM to the diode's banded side,
and the red lead to the non-banded side.

You should get a reading of .4 to .6 on the meter.

Reverse the DMM's leads (red lead to the diode's banded side).
You should get a null meter reading.

Testing a switch diode on a blade/leaf switch, without
removing the diode. The switch doesn't need to beactivated, and
no wires need to be disconnected.

Installing a New Switch Diode.You can replace the diode
with a 1N4004 (or 1N4002 or 1N4001) diode. Make sure you install the
new diode with its band in the same orientation as the old diode
(assuming it's correct!). If you're unsure, compare the diode's band
orientation to a working switch and diode. Most (but not all!)
switches have the green (ground) leads connected to the center
(normally open) lead of the switch. Then the row (white) wire is
connected to the switch lead closest to the center lead (the normally
closed lead). The banded end of the diode is connected solo to the far
(common) switch leg, and the non-banded end is connected to the same
leg as the row (white) wire. There are some exceptions to this
mounting. Your game manual will specify any non-standard switch
installations.

Notice the orientation of the diode's band on these
switches.On a micro-switch, the ground (green) wire usually
goes to the centerlug, the "live" wire and the non-banded side of
the diode to the lug closest to the center. The band on the
diode goes to the solo,far third switch lug. The leaf switch uses
the same connection method(ground to center, banded end of diode
solo). Note there are some exceptions to this mounting.

Switch Matrix Row or Column Problem: the Easy Test.If
you are getting an error message that you have a switch matrix row or
column problem, you need to determine if this is a CPU board problem
or a playfield problem. The easiest way to do this is to unplug the
switch matrix row and column plugs at 1J10 and 1J8. Now enter the
game's diagnostics (coin door center red button down, press the black
button closest to the coin door), and go to the switch edge test. If
the row or column problem is gone (no switch reports), you have a
problem in the playfield wiring. If the problem is still there, you
have a problem on the CPU board. Note most shorted switch matrix
problems are caused by a bad switch matrix column 2N3904 transistor at
Q42-Q49 (which affects the entire column).

Switch Matrix Plug and Pin Numbers.If you are doing
intensive switch matrix diagnostics with the plugs removed at 1J10 and
1J8, you may want to simulate an actual playfield switch closure,
without using the playfield! This can be done by using the internal
switch edge test, and an alligator lead connected to the particular
row/column (switch) in question, and a diode (as described above).

1J8 Switch Column Pin Numbers

Pin 1 = Column 1, green/brown

Pin 2 = Column 2, green/red

Pin 3 = Column 3, green/orange

Pin 4 = Column 4, green/yellow

Pin 5 = Column 5, green/black

Pin 6 = key

Pin 7 = Column 6, green/blue

Pin 8 = Column 7, green/violet

Pin 9 = Column 8, green/gray

1J10 Switch Row Pin Numbers

Pin 1 = Row 8, white/gray

Pin 2 = Row 7, white/violet

Pin 3 = Row 6, white/blue

Pin 4 = key

Pin 5 = Row 5, white/green

Pin 6 = Row 4, white/yellow

Pin 7 = Row 3, white/orange

Pin 8 = Row 2, white/red

Pin 9 = Row 1, white/brown

Testing the switch matrix columns: Using a diode
and a test lead,the test lead is attached to pin 9 of 1J10, and is
stationary. Theother clip holds the non-banded side of the diode.
Then the bandedside of the diode is touched to each pin of
connector 1J8. The"switch levels" test should indicate switches 1,
9, 17, 25, 33, 41, 49, 57when moved from pin 1 to 9,
respectively.

Testing the Switch Columns (all system 11 revisions).To
test the switch columns, do the following:

Remove the backglass and fold down the display to gain access to
the CPU board.

Unplug the connectors at 1J8 and 1J10 (bottom portion of the CPU
board).

Turn the game on.

After the game boots, go to the Test menu's "Switch Levels"
test.

Connect your alligator test lead to pin 9 of 1J10. Pin 9 is the
left most pin, as facing the board.

On the other end of the alligator test lead, clip on a 1N4004
diode, with the banded end away from the alligator lead. Touch the
banded end of the diode to pin 1 of 1J8. Again, pin 1 is the right
most pin, as facing the board.

The display should show switch 1 is closed.

Move the diode/alligator lead on 1J8 to the next pin. The
display should show switch 9 is closed.

Repeat the previous step, until pin 9 of 1J8. Switches 1, 9, 17,
25, 33, 41, 49, 57 should be closed on the display as you move
forward, pin 1 to pin 9, on connector 1J8. Note pin 6 is a key pin,
and should be skipped.

If a particular column number does not display as closed, or is
closed without any test lead connection, there is a problem on the CPU
board. Usually this is a bad switch matrix column 2N3904 transistor at
Q42-Q49.

Testing the switch matrix rows: Using a diode and a test
lead,the test lead is attached to pin 1 of 1J8, and is stationary.
Theother clip holds the banded side of the diode. Then the
non-bandedside of the diode is touched to each pin of
connector 1J10. The "switch levels" test should indicate switches 1,
2, 3, 4, 5, 6, 7, 8 when activated.

Testing the Switch Rows (all system 11 revisions).To
test the switch rows, do the following:

Remove the backglass and fold down the display to gain access to
the CPU board.

Unplug the connectors at 1J8 and 1J10 (bottom portion of the CPU
board).

Turn the game on.

After the game boots, go to the Test menu's "Switch Levels"
test.

Connect your alligator test lead to pin 1 of 1J8. Pin 1 is the
right most pin, as facing the board.

On the other end of the alligator test lead, clip on a 1N4004
diode, with the banded end towards the alligator lead. Touch the
non-banded end of the diode to pin 1 of 1J10. Again, pin 1 is the
right most pin, as facing the board.

The display should show switch 1 is closed.

Move the diode/alligator lead on 1J10 to the next pin. The
display should show switch 2 is closed.

Repeat the previous step, until pin 9 of 1J10. Switches 1, 2, 3,
4, 5, 6, 7, 8 should be closed on the display as you move forward,
pin 1 to pin 9, on connector 1J10. Note pin 4 is a key pin, and
should be skipped.

If a particular row does not display as closed, or is closed
without any test lead connection, there is a problem with the CPU
board.

Testing the Switch Matrix Columns and Rows with a Logic
Probe.If you have a logic probe, you can use this to easily
test the switch matrix:

Remove the backglass and fold down the display to gain access to
the CPU board.

Turn the game on.

After the game boots, go to the Test menu's "Switch Levels"
test.

Unplug the connectors at 1J8 and 1J10 (bottom portion of the CPU
board).

With your logic probe connected to power and ground, probe each
pin 1 to pin 9 of 1J8 (pin 1 is the right most pin, as facing the
board). These are the switch columns. All pins should show PULSE on
the logic probe.

With your logic probe connected to power and ground, probe each
pin 1 to pin 9 of 1J10 (pin 1 is the left most pin, as facing the
board). These are the switch rows. All pins should show HIGH on the
logic probe.

Resistor Network Testing/Explaination used in the Switch
Matrix.The resistor networks in the switch matrix can fail,
and this is fairly common. There are two types of resistor networks
used on the system 11 CPU board; "Bussed" and "Isolated".

If a resistor network is "560 x 8" and has 9 pins, that means it's
BUSSED; all the resistors are tied to one common pin (this pin is
labeled with a white square around it on the circuit board). Simply
put, if a resistor network has an odd number of pins, it is probably
bussed.

If a resistor network is "1K x 4" and has 8 pins, this is an
ISOLATED resistor network; a bunch of resistors in the same small
package, so it uses two pins per resistor. Simply put, if a resistor
network has an even number of pins, it is probably isolated.

Left:
A bussed resistor network. Right: An isolated resistor
network.

Here are the different resistor networks used in the system 11
switch matrix:

When testing a BUSSED resistor network, first find pin 1. This pin
will have a white square around it, to isolated it from the rest of
the pins. Use a DMM set to ohms, and put one lead on pin 1. Put the
other lead on each pin 2 to 9. The same reading should be seen for
each pin 2 to 9.

When testing an ISOLATED resistor network, put the DMM leads on the
two adjacent pins furthest to the right or left, and note the reading.
Then move both DMM leads down one pin. The same value should be seen.
Continue down the resistor, moving both DMM leads one pin at a time,
until all adjacent pins are tested.

A bussed
resistor network. Note the white square around pin 1; this is
the common pin.

A "hacked"
bussed resistor network. If the correct resistor networkcan
not be found, this shows how to make a bussed resistor network
from individual resistors. Note the white square around pin 1;
this is the common pin. This picture shows quite well how a
bussed resistornetwork is wired.

Bad Switch Column: How to Fix it.Usually the switch
column transistors fail here. These are 2N3904 transistors at Q42 to
Q49. See the Checking
Transistors section for details on testing these transistors.
Right before the transistors there is a capacitor network; this rarely
fails (and is not documented in the list below). Next each one of the
eight transistors connects to a 1.5k resistor at R71 to R78. Then the
resistors at R71 to R78 connect to a resistor network at SR15. This is
a group of eight separate 4.7k ohm resistors, in a single package.
Measure the resistance between pins 2 to 10 of SR15, and pin 1 of SR15
(the common pin). You should get 4.7k ohms for each connection:

1J8 pin 1, to Q45, to R77, to SR15 pin 2, to U40 pin 18 (column
1).

1J8 pin 2, to Q49, to R78, to SR15 pin 3, to U39 pin 3 (column
2).

1J8 pin 3, to Q44, to R75, to SR15 pin 4, to U39 pin 16 (column
3).

1J8 pin 4, to Q48, to R76, to SR15 pin 5, to U39 pin 5 (column
4).

1J8 pin 5, to Q43, to R73, to SR15 pin 7, to U30 pin 14 (column
5).

1J8 pin 6: KEY

1J8 pin 7, to Q47, to R74, to SR15 pin 8, to U30 pin 7 (column
6).

1J8 pin 8, to Q42, to R71, to SR15 pin 9, to U30 pin 12 (column
7).

1J8 pin 9, to Q46, to R72, to SR15 pin 10, to U30 pin 9 (column
8).

If the transistors and resistor network checks out good,
next replace chip U40 (74LS244). If there is still a switch matrix
column problem, replace the PIA at U38 (6821) last.

Bad Switch Row: How to Fix it.First check the 560 ohm
resistor network at SR11. This is a group of eight separate 560 ohm
resistors, in a single package. Measure the resistance between the
pins 2 to 10 of SR11, and pin 1 of SR11 (the common pin). You should
get 560 ohms for each connection. Then check the 1k ohm SR10 between
the SR11 pin and the stated pin on U39/U40 below. You should get 1k
ohms for each connection:

If the resistor networks check out good, next
replace either U39 and/or U30 (a 4011 chip) (depending on which switch
row number is dead). If you are still having a switch matrix row
problem, replace the PIA at U38 (6821) last.

Further Diagnosing of the Switch Matrix.If you are
having a switch matrix problem, the first plan of attack is to do the
above column and row switch matrix tests. If these tests pass, the
problem most likely is in the wiring. Note most switch failures show
as Row failures (even though it could be a column problem). Here are
eight different ways the switch matrix can fail. All require you use
the internal "switch level" or "switch edge" tests of the game.

Switch column shorted to ground.When a column wire is
shorted to ground, and any switch in that column is closed, the
switch test will show ALL switches in the ROW of the closed switch
as being closed. If no switches are closed, the switch test will
show no switches closed. To find the location of the short, go to
the end of the switch column wire on the playfield (the switches are
"daisy chained" together for an entire column or row). Then break
the daisy chain one switch at a time until the short no longer shows
in the switch test.

Row shorted to ground (diode anode).When the anode
(non-banded end of the switch diode) is shorted to ground, the
switch test will show the entire row as activated (whether any
switches are closed or not). To find the location of the short, go
to the end of the switch row wire on the playfield (the switches are
"daisy chained" together for an entire column or row). Then break
the daisy chain one switch at a time until the short no longer shows
in the switch test.

Row shorted to ground (diode cathode).When the
cathode (banded end of the switch diode) is shorted to ground, that
switch's entire row will show as closed in the switch test (whether
the switch is open or closed). To find the location of the short, go
to the end of the switch row wire on the playfield (the switches are
"daisy chained" together for an entire column or row). Then break
the daisy chain one switch at a time until the short no longer shows
in the switch test.

Column wires shorted together.When two column wires
are shorted together, and none of the switches in those columns are
closed, the switch test will show no problems. But pressing any
switch in either column will show that switch, along with a switch
in the column that is shorted on the row of the switch you are
closing. For example, if column 2 and column 4 are shorted together,
closing switch column 2 row 3 will also show a closed switch in
column 4 row 3.

Row wires shorted together.When two row wires are
shorted together, and no switches are closed, the switch test will
show no closed switches. When any switch on either row is closed,
another switch on the same column as the closed switch will also
show as closed. For example, if rows 1 and 4 are shorted, closing a
switch in row 1 column 3 will also show a closed switch on row 4
column 3.

Column and row wires shorted together.When a column
and row wire are shorted together, the switch test will show the
switch that is at the intersection of the row and column as being
closed, even though it is not closed. All other switches on all
other rows and columns will work correctly. For example, column 1
and row 3 are shorted together. The intersection of this column and
row will show that switch as closed (even if it's not). And
remember, this switch is not what is causing the problem!

Open diode on a switch.An open diode on a switch will
cause only that switch not to work.

Shorted diode on a switch.A shorted switch diode will
show no problems when only that switch is opened or closed. However
if additional switches in that row or other columns are closed,
false switch readings can be shown.

Switch Maintenance.Here are the procedures for
maintaining your WPC switches:

Micro-switch: no maintenance required. Can adjust the actuator
arm only by rotating the switch in its bracket. Do not BEND the
activator arm! Loosen the two screws holding the switch, and rotate
the switch to adjust the activator arm. Re-tighten the screws, but
not too tight as it will bind the switch mechanism.

Blade or Leaf switch: clean with a business card inserted
between the contacts. Squeeze the contacts closed, and remove the
business card. Do not use a file on these gold plated contacts!
Re-adjust the contact spacing for correct operation.

Opto switches: use a Q-Tip and some Windex. Dip the Q-tip in the
Windex, and clean the opto's two LED's (receiver and transmitter)
with the Q-tip.

What is that loud "Popping" when I turn my Game On?"I
have this problem when I power-on my game; the free game knocker
'pops' with a loud knocking 4 or 5 times, then finally stops and the
game starts up and does appear to play correctly. I get a message at
the beginning when this happens to 'adjust switch outside loop' and
#35 shows up in my fourth player score display."

What the game is trying to tell you is that switch #35 has not been
actuated (ie: closed) in about 30 games or so. That's usually
sufficient reason to suspect that the switch as bad. The game will do
its best to compensate for the bad switch (by using other switches
around it), but it is trying to say that the switch needs to be looked
at.

Inside the coin door there should be three operator diagnostic test
switches. Make sure the middle one is in the "Down" position, and then
press the one marked "Advance" or "Enter". This puts the game in Test
mode. Keep pressing Advance until you see the "Switch Edges" test
(remember at this point the playfield is "live", so watch those
pop-bumpers, slingshots and flippers). Now verify that the bad switch
really doesn't work by activating it. Test it using the ball if
possible and not just your hand.

Now turn the game off and remove the balls and lift the playfield.
Locate the switch under the playfield. There should be a bunch of
"blade" (or possibly micro) switches. The one that doesn't work may
have a broken wire, or some other sort of mechanical failure. If it is
a leaf switch, it may simply be dirty. Find a business card and gently
press the switch leafs closed, and pass the card between the two
contacts. These switch contacts should be gold flashed, so don't use
anything abrasive (the business card is all that is needed).

The leaf switch could also be out of adjustment. There is one
moving blade, and one stationary blade. To adjust the switch, bend the
*stationary* blade only to move the switch contacts closer. Test the
switch with a ball to make sure it is working correctly.

If the game has microswitches, a simple adjustment to the activator
arm may be in order, or the switch itself has failed.

Test the switch again in switch test, and see if this solves the
problem. If it doesn't, check for a problem with a broken wire on a
nearby switch. The switch wires "daisy chain" from switch to switch in
the same row/column. So a non-working switch could be a broken wire
"upstream".

Williams also used optic light emitting diodes (LED's) for some
switches, even on the older System 11 games. Mostly Williams used "U"
shaped optics for detecting the position of drop targets. The problem
with this is vibration. Often the optics will actually break off the
circuit board because the drop targets take so much abuse.

The optic board from a pre-system 11b drop target (note
the lack of any chips on this board). You can use Radio Shack's infrared
detector card to see if the opto transmitters are working. On these
older optics, the "red" side is the transmitter, and the "white" side is
the receiver. The transmitter is the side that 95% of the time dies.
After all, it's essentially a light bulb that can burn out.

If a drop target is not sensing when it is down, it's a good
chance you have an optic problem. The optic board is held to the drop
target with three "E" clips on rubber mounts. Remove the "E" clips and
the board will lift off the drop target assembly. Now inspect the
optics. If they are not broken, clean them with a Q-tip dipped in
Windex. It is amazing how often just cleaning optos in this manner
fixes them.

Optos have two sides to them: a transmitter, and a receiver. The
transmitter is the part that fails 95% of the time. Essentially the
transmitter is a light bulb, and all light bulbs burn out eventually.
And the optics are always "on", even when the game is in attract mode
(another good reason to turn your game off when not in use).

A nice tool to have in your tool box is the Radio Shack infrared
detector card. This $5 credit card sized card will show if the optic
transmitter is producing light. Without this card, you can not see
this wave length of light. So this handy little card is quite good to
have. Remember you must have the card positioned in front of the
transmitter to see the light on the orange colored band (having it in
front of the receiver won't show anything!). The "red" side of the "U"
shaped opto is the transmitter side of the optic.

System 11b and Later Optic boards.With system 11b, the
optic circuit was removed from the CPU board. This meant that the
optic board (for example on drop targets) needed added circuitry to do
the switch processing. This was done by adding LM339 chips to the
optic board. If you are having problems with an optic board, and you
know the optics themselves are good, suspect the LM339 chips. These
are inexpensive chips; just replace them wholesale on the optic board
if in doubt.

New Style Optics on Optic boards with LM339 Chips.The
optics themselves were changed on the newer optic boards with LM339
chips. The new optics used new style "U" shaped optics (as used in the
1990 and later WPC games). Unfortunately this new style of optics had
a much bigger problem with breaking leads, and falling off the optic
board. Whenever replacing these optics, put a dab of silicone
underneath the optic when mounting them to help prevent this problem.

Replacing the Optics.Be careful installing new optics.
It DOES matter which way you install them! If you install the new
optic backwards, you will probably ruin it. Remember on the old style
optic boards, the red side of the optic is the transmitter. On new
style optics, the side of the optic with the white "dot" or the
"notch" is the receiver. The white dot on these new style optics
matches with a corresponding white dot on the circuit board, to make
installation easy. Also use a dab of silicon under the optic when
mounting them. This will give them some shock resistance.

3m. When thing don't work: Score Display
Problems

One of the most frequent system 11 problems relates to non-working
or weak score displays. Fortunately, often there is a very easy fix
for this problem.

The simplest thing to check when the score displays do not work is
the +100 and -100 volt DC power section of the power supply. If either
of these voltages are bad, your displays will not work. And quite
often, this power supply section does go bad.

The 39k ohm Power Supply Resistors.The major villain in
the system 11 power supply is resistors R1 and R4. These are both 39k
ohm, 1 watt resistors. Very often either or both of these resistors
will go out of spec, or even completely open. This will prevent the
+100 and/or -100 volts from getting to your score displays On newer
WPC games with alphanumeric displays, these are resistors R48 and R49
on the alphanumeric display board.

Note the score display is barely working. At first, you
may think it's the display glass itself. This is infact a common
problem, where the displays "outgas" and don't show as brightly, and
eventually completely die. But before you change the expensive score
display glass, change the 39k ohm resistors on the power supply with new
1 or 2 watt "flameproof" resistors.

Here is the same score display after the 39k resistors were
changed on the power supply board. This cheap 50 cent fix shows that the
score display glasses themselves were good!

If your high voltage fuses are not blown, and your score displays
do not work, first replace the 39k ohm resistors. These are cheap and
easy parts to replace (a lot cheaper and easier than replacing score
display glass!). Or at least check these. Replace these two resistors
with "flame proof" 1 or 2 watt 39k ohm versions. And make sure you
mount the new resistors slightly off the circuit board, so air can get
under them for cooling.

Check the +100/-100 volts at the Power Supply board.It's
really easy to check the +100 and -100 volts at the power supply
board. These voltages should be from 95 to 105 volts. Check for these
voltage at power supply connector.

Power Supply D-8345-xxx (where xxx is the game number). Used from
High Speed to Swords of Fury ??.

Power Supply Diodes Leak.Like resistors the two 39k ohm
resistors, the two diodes at D1 and D3 (1N5990) can start to "leak"
(on WPC alphanumeric games, diodes D1 and D2 on the alphanumeric
display board). If your displays are weak and your 100 volt section is
low (even with the score display glass unplugged), try changing these
two diodes (after you change the 39k ohm resistors first).

Blown high voltage score display Fuse(s) in the
Backbox.Every system 11 game at least one fuse to protect the
+100 and -100 voltages which power the score displays. Later games
have more than one fuse. These are located in fuse holders in the
backbox. If these fuse(s) are blown, try replacing them, and power the
game back on. If they blow again immediately, you will probably need
to rebuild the high voltage section of the power supply board.

Also a blown UDN7180 chip on the master display board can cause the
high voltage fuse(s) to blow on the power supply board. These chips
can short the +/- 100 volts directly ground, and blow the fuse.

Increasing Score Display Life.Glass score displays are
getting very expensive. Because of this, it is important to make your
current glass score displays last as long as possible. The best way to
do this is to decrease the 100 volts (which powers the displays) to 91
volts. This can be done by replacing the zener diodes at ZR2 (Z2) and
ZR4 (Z4) to a lower voltage diode

The original diodes used at ZR2, ZR4 are 1N4764A. These are 100
volt, 1 watt zener diodes. If you replace these with 1N4763A diodes,
which are 91 volt, 1 watt zener diodes, only 91 volts (instead of 100
volts) will power the displays. This will make your displays slightly
less bright, but it will also DRAMATICALLY increase their life span!
Since glass score display tubes are becoming so expensive, this is
highly recommended. Note on the newer WPC alphanumeric games, diodes
D5 and D6 were changed to 1N4763 diodes from the start.

The high voltage section of the power supply.

Rebuilding the 100 volt Power Supply Section.If any of
the high voltage fuses are blowing, you probably need to rebuild the
100 volt power supply section. You will need to replace the following
parts on the power supply board.

Positive System 11 100 volt section parts to replace:

Q1 = MJE15030 transistor. On older games that specify a SDS201
transistor (which is no longer available), the leads of the MJE15030
transistor must be "twisted" so the emitter, base and collector
match the circuit board. You can also use a MJE340 (NPN 300 volt
transistor) or a 2N3440 with a "star" heat sink.

Q3 = MJE15031 transistor. On older games that specify a SDS202
transistor (which is no longer available), the leads of the MJE15031
transistor must be "twisted" so the emitter, base and collector
match the circuit board. You can also use a MJE350 (PNP 300 volt
transistor) or a 2N5416 with a "star" heat sink.

A replacement MJE15031 in an older system 11power
supply. The leads on the MJE15030 and MJE15031 must be "twisted" to
replace the older SDS201 and SDS202 transistors. This shouldONLY
be done on power supplies that originallyused the older SDS201 and
SDS202 transistors.

When installing the new parts, cut the old parts out first. Then
use a solder sucker and clean out the circuit board holes. Make sure
you install new resistors slightly off the board, to allow for air
circulation. Solder all parts on both sides of the board.

When installing the newly fixed board, measure the output voltages
BEFORE you plug in the connectors going to the score displays! Output
voltage should be between 95 and 105 volts.

Score Display Ribbon Cable Problems.System 11 and WPC
alphanumeric games have a fairly small problem that can appear to be a
major one. If you have had the CPU board out of your game, and now
your score displays don't work, check the ribbon cables connecting to
the CPU board. It is very easy to install the cables offset by 1 pin
to the left or right. In most cases this will not damage the
electronics. And always make sure the red strip on the edge of the
cable lines up with pin number one on the CPU board connector.

Slow Display Strobing Problems.Sometimes the score
displays can have a slow reveal and wipe pattern that leaves only
three or four digits on at a time. This can show as three or four
digits in the player one and three displays, then the credit display,
and finally the player two and four displays. Then the next three or
four digits display the same way across all the score displays. You
never see the entire display lit. The game will do this in game or
game over mode, just repeating the pattern. The score displays do
however keep score accurately. Also this problem can sometimes be seen
in a single score display.

This is usually caused by weak high voltage going to the score
displays. Instead of plus or negative 100 vdc, the voltage can be as
low as 50 volts. This low voltage can be caused by resistors R1 and/or
R4 (39k ohms) on the power supply board, or a bad high voltage
capacitor C1/C3 (100 mfd 250 volt), or C2/C4 (0.1 mfd 250 volt metal
polyester cap) on the power supply board.

Partial Segment Failures on Score Displays.Sometimes
only parts of a display aren't displaying, and only on certain
numbers. For example, the top part of a "0" or "7" are not displaying.
It can even be so strange so that the missing segment will work on
some numbers or letter, but not on others.

This can be caused by one of the hex input buffers at U10, U11,
U15-U18 (14050 or 4050) on the Alphanumeric master display board,
which are CMOS chips and static sensitive. You can check these with
your ohm meter. Connect one lead to ground, and the other lead to each
input/output pin of the 4050 chips. Any pin that doesn't read the same
as the others probably means the chip is bad. Sometimes you'll have to
test these chips with an analog ohm meter, and watch the needle
"bounce". A pin that doesn't "bounce" like the others again probably
means that chip is bad.

More Segment Problems: the UDN7180 chip.If you are
having display problems (and you have fixed the power supply board),
the next course of action is to check the UDN6118 and UDN7180 chips on
the Master display board. The UDN6118's control the strobe pulses, and
the UDN7180 control each segment in the display. Usually the UDN7180
is the one that fails (and are unfortunately hard to get and somewhat
expensive). There are as many as four UDN7180's and UDN6118 chips on
the master display board.

Both these chips are easy to test: both have an input and output
side. If the input side is pulsing (check this with your logic probe),
then a good signal is probably getting to the chip. Next check the
output side. It should be pulsing too. To test these, put the game in
it's diagnostic display test. Then single stepped to the next digit
test (all zeros, 1's, 2's, etc) and check the input and output pins at
each step. If the input side is pulsing, and the output side is not,
then the chip is probably at fault.

The UDN6118 and UDN7180 both have the same pinout: pins 1 to 8 are
the input side of the chips, and pins 11 to 18 are the output side.
Check the schematics to see exactly which chip controls which display
when diagnosing these. Here's an example:

Answer: looking at the display board schematic found that U13, U14
(UDN7180) are common components to these displays. Chip U13 drives
segments "h,j,k,m,n,p,r" and the period, while U14 drives "a" to "g"
and the comma. Since UDN7180's are becoming rare and are expensive,
the input and output signals were double checked by comparing them
with a logic probe (or an oscilloscope). Putting the game in display
test so it could be single stepped to the next digit test (all zeros,
1's, 2's, etc). On chip U14, the input pins 1-8 showed activity and
changed when I advanced to the next digit test. Next tested the U14
output pins 11-18. The output pin 18 (for the "b" segment) was
constant and did not change when the test was advanced. The conclusion
was to removed and replace the UDN7180 at U14 (after installing a
socket), which fixed the problem.

Segment Still doesn't work: Check the Resistors before replacing
a UDN7180.Since UDN7180 chips are expensive and hard to find,
you want to make sure it really is the problem before you replace any.
If you have checked/replaced the 4050 chip(s) and probed the UDN7180
and UDN6118 chips, there is one more thing you should check. That
would be the resistors coming off the UDN7180 chips. Though it doesn't
happen a lot, a bad resistor solder joint or bad resistor itself could
be your problem.

Check these resistors with your multi-meter to make sure they are
at the correct value. Using the schematics, find the segment letter
identifier you are missing. Then follow that segment through the
UDN7180 and its corresponding resistor. Make sure that resistor is
within 10% of the schematics specified value. Or if you don't have a
schematic, just check ALL the resistors on the Master display board
with your multi-meter. The slightly larger 1/2 watt resistors tend to
be the more troublesome resistors.

"Outgassed" Score Displays.Score display glass has a
limited life; it does not last forever. Time will eventually kill
these, and the display will "outgas" and fail. Because of the high
voltage involved with score displays, the anode and/or cathode inside
the diplay glass breaks down. This results in the "outgassing" of
impurities that eventually change the internal gas properties, so the
display can't glow (the gas must be very pure for the display to
work). There is no fix for this short of replacing the display glass
(which have become fairly expensive now). Sometimes score glasses
short too.

Two Versions of the Alpha-Numeric Display Boards.Taxi
and Police Force use a slightly different style of display board. Both
these games have an extra score display. In order to accomodate this,
the standard system11 alpha-numeric display board was modified
slightly.

Taxi and Police Force have an alpha-numeric display at the top, and
an alpha-numeric display which is only used for numerics on the bottom
in the backbox. The reason for this is that when they installed the
extra display they needed a way to run it. The bottom 16 digit display
on these games only uses 8 segments (the middle segment of the display
is used to make the number zero into an eight, which is two segments).
This leaves six segments and the "comma" left unused. The unused
segments are then used to drive the extra display. This is the reason
there's a second place to hook up a ribbon cable on the Taxi/Police
Force display boards.

The Taxi/Police Force style display board can be converted to work
in the other 16 digit alpha-numeric system 11 games, with a small
modification. Simply install the missing seven resistors into
locations R62 to R68 on the Taxi/Police Force display board.

System 11 power supply schematic from Big Guns (games with
Auxiliary power supply boards) to Cyclone. The only difference in power
supplies after Cyclone is the lack of GI connectors on the power supply
board (these were moved to the Interconnect board).

Often when you buy a used system 11 game, upon power up, you'll get
an error message stating, "Adjustment Error" (if the coin door is
closed) or "Factory Setting" (if the coin door is open). This message
indicates that the CPU RAM chip at location U25 on the CPU board has
forgotten the game's bookkeeping and options settings.

If the coin door is closed, and the batteries are dead,
you'll get an"adjustment error" message.

If the coin is open, and the batteries are dead, you'll get a
"factory setting" message. You can also get either above
messageif the battery holder is bad, or the RAM chip at U25 has
failed.

The difference between these two messages is simple; when the coin
door is closed (and the memory protect switch which is connected to
the coin door is pressed in), the CPU is electrically blocked from
accessing the RAM at U25. Therefore the game can only reset the
factory settings if the coin door is open. If the game ever comes up
with the "Adjustment Failure" message, the coin door must be opened to
get past this message.

Why Do I Get These Error Messages?Most often, these
errors occurs because the three "AA" batteries on the CPU board have
died. These batteries should be replaced every year with good quality
alkaline batteries (batteries are cheap, battery damage is expensive).
The three batteries must keep at least +4 volts of power to the U25
RAM chip for it to remember. When power goes below +4 volts, memory
reset can occur (and you get the "Factory Setting" error message).

A bad battery holder. At first glace, this holder looks
fine. But the two battery contact points on the left have corroded and
fallen off. The contact on the right is the only one intact. These
contact points are actually rivets, but corrosion will cause the face of
the rivet to break as it goes through the fiber insulator, and the face
of the rivet that contacts the battery falls off.

The Battery Holder: a Weak Link.If after replacing the
batteries, you still get a "Factory Setting" error, suspect the
battery holder. Use your DMM and check the battery voltage at the CPU
board. With the game off, put your DMM on DC volts and put the black
lead on ground (the grounding strap or on one of the screws holding
the CPU board in place). Put the red lead on each of the CPU board's
POSITIVE battery terminal SOLDER POINTS. Test each of the three
batteries' positive leads individually. You should get about 1.5, 3.0,
or 4.5 volts at each battery (note the batteries are additive and the
first battery in the chain will give you 1.5 volts, and the last
battery will give you 4.5 volts). If you don't these positive
voltages, suspect damaged battery holder terminals. These corrode
quite often if new batteries aren't installed religiously. Replace the
battery holder and re-test to ensure proper repair.

A battery gone bad. Note the white "fur" on the bottom of
the battery, and how it has corroded the chip and socket below it. The
battery holder, chip and socket must all be replaced. Also the board
must be washed with a mixture of 50/50 water and white vinegar (a mild
acid) to neutralize the alkaline battery gunk, and then rised with
water. After drying, the corroded areas can be sanded clean to the bare
copper traces, and the components replaced. If the board isn't washed
with this vinegar solution, the corrosion will return.

A Better Replacement Battery Holder.The best battery
holder to buy is the new black plastic battery holder used in WPC-S
and later games. This is Williams part# A-15814. This design of
battery holder is much better than the original system 11 design, and
will fit perfectly on a system 11 CPU board.

Testing for Battery Voltage.After testing the batteries
at the battery holder, test for voltage at the blocking diode D2
(1N4148), which is next to the left bottom side of the battery hold on
the CPU board. With the game off, put the black lead on the backbox
ground strap, and put the red lead on either side of the diode. You
should get around 4.2 to 4.8 volts. The banded diode of the diode
connects to the U25 RAM chip pin 24, and should be about .5 volts less
than the non-banded side of the diode. If you only get voltage on only
one side of the diode (the non-banded side, which connects directly to
the battery), the diode is bad and needs to be replaced.

Next check for voltage at the U25 RAM chip. With the game off, you
should get about 4.3 volts DC at pin 24 of chip U25 (ground is pin 20
by the way). If you don't, the battery voltage is not getting to the
U25 RAM chip. This will cause the game will boot up with the "Factory
Setting" or "Adjustment error". Note pin 24 of the 24 pin RAM chip is
in the same position as pin 1 of the chip, but on the opposite row of
pins. Pin 1 is designated with an impressed "dot" right on the top of
the chip. This chip is a 2k by 8 CMOS static 24 pin RAM chip. The part
number will be 2016 or 6116-L or NTE2128. Early system 11 games
specify this chip as a 5177, but this chip can be replaced with a 6116
instead.

You can still have problems even if you installed new batteries and
all the voltages check out. If your game is still giving "Factory
Setting" or "Adjustment error", you may have a bad CPU U25 RAM chip.
But make sure you double check that battery holder. Even minor
corrosion can cause this problem. The voltages may all check out, but
the corrosion may be enough to limit CURRENT, and cause this problem.

More "Blocking" Diode D2 Problems.The three AA
batteries are connected to the U25 RAM chip via a "blocking" diode.
This 1N4148 switching diode at D2 is connected in series between the
battery and the U25 RAM chip. It's job is to prevent +5 volts from
going back to the batteries (it only allows power from the batteries,
not to them). Sometimes this diode shorts out or goes open. If this
diode shorts, the CPU board will try and charge the three AA
batteries! This will cause the batteries to leak, and could damage
your CPU board. If the diode goes open, the batteries will never power
the U25 RAM chip, and the game will boot up with the "Factory Setting"
or "Adjustment error". Check this diode with the game off and your DMM
set to the "diode" setting. You should get between .4 and .6 volts in
one direction, and a null reading in the other direction. You can also
test the diode (with the game off) by setting your DMM to DC volts.
Put the black lead on ground, and you should get 4.2 to 4.8 volts on
either side of diode D2 (the banded side will be about .5 volts
higher). If you only get voltage on one side, the diode is open and
needs to be replaced.

Changing
Batteries.If your game is working, and it's time to replace
the batteries, follow this procedure. But the way, you should change
the batteries in your game every year, or every two years at most (to
prevent any battery leakage problems):

Remove the backglass and gain access to the CPU board.

Turn the game ON.

Note the orientation of the installed batteries (All positive
terminals up or to the right?).

Remove the old batteries and discard.

Check the battery holder's terminals for any corrosion. Clean
with 220 grit sandpaper if any corrosion. If damaged, turn game off
and replace battery holder.

Using a Sharpie pen, write today's date on the new batteries.

Install the new batteries.

Turn the game off.

If you install new batteries with the game turned on, the machine
will not forget the old option settings or bookkeeping totals.

Clearing a "Factory Setting" or "Adjustment Error"
Message.To clear these messages, you first need to fix the
problem (replace the batteries and/or battery holder, replace the U25
RAM, etc.). After this is done, turn the game on. Then press the
center red coin door button into the down position. Now press the
black button closest to the coin door. If you have an "adjustment
error", the game will beep and flash the "factory setting" message.

Once you have the "factory setting" message, press the black button
closest to the coin door twice. Then move the center red button to the
up position. Then press the black button closest to the coin door
again (twice if you had an "adjustment error" message). The game
should now go into attract mode.

New CPU Batteries Die very Quickly.Just to the side of
the battery holder on the CPU board, there are two "blocking" diodes,
D1 and D2. These form a diode bridge, blocking the battery voltage
from the power supply, and vice-versa. Where these two diodes meet,
power goes to the U25 RAM. This way when the game is on, power for the
U25 RAM is drawn from the power supply. But when the game is off,
power for the U25 RAM is drawn from the batteries.

If either diode D1 or D2 is bad, it can let the batteries attempt
to power all the +5 volts logic for the whole CPU board when the game
is powered off. Or it can let the +5 volts from the power supply
attempt to charge the batteries when the game is powered on. In either
case, this will cause the batteries to die quickly.

If you have batteries that are dying very quickly, replace both
diodes D1 (1N5817) and D2 (1N4148) on the CPU board.

3o. When thing don't work: Miscellaneous
Oddities

Problem: In attract mode, the pop bumper coil on my F-14
behaves normally (did not fire or energize). Once a game was started
or test mode entered, the coil would fire and stay energized. In
attract mode, the coil could be fired by hitting the pop bumper skirt
switch (this is NOT normal behaviour, and the others pop bumpers did
not work this way)! Grounding the metal tab of the Q69 TIP122
transistor while the game was in attract mode energized the coil and
released it (properly).

Answer: A close look at the 7402 chip at U50 (which is the
controlling TTL for this coil) revealed that pins 5 and 6 where
shorted together. This was caused by a solder splash from a previous
repair. Removing this short fixed the problem!

I turn my system 11 game on, and the score displays will only
show 0's and X's in the middle of them.Problem: the game
thinks you have "slammed" it.

Answer: there is a slam switch inside the coin door, just above the
coin door lock. This switch should be normally open. If this switch is
shorted or bent closed, you will have this problem. Often people will
accidentally bend this switch when putting credits on the game (a good
reason to have the game set on free play!). If the switch is not
shorted closed, the switch matrix could also be damaged, as the slam
switch is part of the switch matrix. See the Switch Matrix
section of this guide for info on fixing that.

A system 11 game coil is always energized.Problem: "I
have a system 11 game with solenoid problems. I have replaced the
TIP122 transistor, the associated pre-driver transistor, the 7408
chip, and even the 6821 PIA. But nothing keeps the solenoid from
staying energized."

Answer: some 50 volt coils are driven by a TIP36 transistor on the
Auxiliary power driver board. If the TIP36 is shorted, the coil will
stay energized (regardless of what you replaced further up the
electronic river).

"When I turn my Fire! game on, the score displays would flash
quickly at a high brightness, and the speakers would be noisy, but the
game does nothing more."Problem: the CPU board has a blanking
circuit problem. The job of the blanking circuit is to shut down the
score displays, solenoids and lamp circuits if there is a problem on
the CPU. This safety circuit also protects other circuits during
power-on if there is a problem.

Answer: there were two failed components, a 555 timer chip at U43
and a bad 2N4403 transistor at Q50.

To test the blanking circuit for proper operation, check U20 pin 2
or U43 pin 3 at power-on, using a logic probe. You should get an
initial LO for a few seconds, followed by a continuous HI after the
game has booted.

All score displays are out, game will start but flippers and
ball eject do not work. While the game was being played (when it
worked) the displays began acting strangely then the game died. Any
further attempts to start a game resulted in above problems.

Answer: Examining the display board discovered a glob of flux on
U11 (4050 hex buffer) shorting pins 14 and 15 together. Using the
schematics and wiring diagrams was able to trace those pins back to
the CPU board. The short killed U51 (PIA 6821) on the CPU board.
Removed U51 (6821), added machine pin socket, and replaced it with a
new 6821 PIA.

"No Sound on my Pinbot."Problem: The sound on the Pinbot
just suddenly died. The amplifier section seems to work, because when
the volume control is turned, you can hear the scratching sound coming
from the speakers. Also when the sound test button is pressed on the
CPU board, you can faintly hear the sounds.

Answer: No -12 volts DC, which is used for the sound. In this case
it ended up being the bridge rectifier that converted the 12 volts AC
to DC voltage that had failed.

When the flipper button is pressed, the game resets. When the
ball hits the slingshot, the game tilts.Problem: This is a
switch matrix problem. The low voltage (high score) switch on the
flippers and the slingshot scoring switch are triggering other
switches in the switch matrix.

Answer: First I would suggest looking for a bad, missing or
mis-wired switch diode. But in reality this was not the problem. A
switch matrix column transistor (2N3904) was bad, as was the switch
matrix column resistor network SR15.

The CPU software for Road Kings on the Williams web site does
not seem to work.

Answer: Indeed the EPROM software for Road Kings on the Williams
web site is bad. For working software, click here for
working EPROM files.

On My F-14, I need a new rubber belt to drive the rotating
beacon lights. Where can I get this?

Answer: This rubber drive belt is available from any local John
Deere tractor store! Just ask for part number H85996, cost is about
$2.00.

4a. Finishing Up: Rebuilding Flippers

Regardless of your playing skill, the one thing everyone notices
about a pinball game is the flippers. Novices and pros alike can tell
you if your game has good, powerful flippers, or whimpy, limp, dead
ones. Flippers are the interface between the game and the person
playing. If you don't maintain anything else on your game, at least
maintain the flippers. Games with good flippers are fun. Games with
bad flippers aren't fun (regardless of what the game title is).

Flippers get weak because they have moving parts that get
substantial use. When they wear, the mechanisms get play (slop) in
these moving parts. Instead of the flipper coil transmitting all its
energy in propelling the ball, some energy is absorbed by the sloppy
mechanisms. Rebuilding the flippers removes this slop, and will
dramatically increase the strength and feel of your flippers.

How Flipper Coils Work.Flipper Coils are a unique type
of solenoid. This coil is actually two coils in one package. One part
of the coil is the high-powered side. This uses large diameter wire,
with a limited number of turns (low resistance). Since there is low
resistance, the power can travel quickly and easily through these
windings. This part of the coil gives the flipper its initial power to
kick the ball.

The second part of the flipper coil is the low powered side. This
acts much like a hold relay; lots of turns of thin wire with high
resistance. This part of the flipper coil is intentionally shorted out
and turned off by a normally closed end-of-stroke (EOS) switch.

Left: Note the capacitor to minimize EOS switch
arc on a parallel wound flipper coil, and the style of return spring
used. The EOS switch is a high voltage, Tungsten contact, normally
closed switch. Trivia question: what is wrong with this flipper
coil?Answer to the above trivia question ("what's
wrong with the above picture's flipper coil?"):The problem shown on
the left is the flipper coil is installed upside down!. The wire
terminals that the flipper coil wires connect should be as far away from
the coil stop as possible. The coil stop is where most flipper vibration
originates. The coil plunger slams into the coil stop, causing
vibration. This vibration will eventually break the coil wires off of
the coil wire lugs. To minimize this, the coil is mounted so the wire
lugs are further away from the coil stop. Unfortunately, Williams didn't
identify this problem on system 11 games, so usually the wires are too
short to install the coil correctly!

Flipper Differences.Flipper worked different on games
High Speed to Millionaire. These games used a series wound
FL23/600-30/2600 flipper coil. The common lug (where both the low and
high powered coil wires were connected together) on these flipper
coils was the middle of the three lugs. Also these coils used ONE
diode across the two outside lugs. The EOS switch on these games, when
opened, enabled BOTH the high power and low powered coils together.
This style of flipper coil did NOT use a 2.2 mfd anti-spark EOS
capacitor. The problem with this series wound coil was the "back
spike" of current that occured when the EOS switch was opened. This
cause the EOS switch to excessively wear and pit.

With the introduction of F-14 Tomcat, Williams changed to the
parallel wound FL11630 style flipper coil. This coil now used an
outside lug as the common lug (where both the low and high powered
coil wires were connected together). Also TWO diodes were used and
required on these flipper coils. This parallel wound coil eliminated
the "back spike" of current when the EOS switch opened. It also
allowed the use of a 2.2 mfd 250 volt capacitor to further limit EOS
switch sparking and pitting. Now when the EOS switch opens, this
removed the high powered side of the coil from the circuit. The low
powered side of the flipper coil is always in the circuit, but is
essentially ignored when the high powered side is in the circuit. This
happens because the current takes the easiest path to ground (the low
resistance, high power side of the coil). The low power high
resistance side of the flipper coil won't get hot if the player holds
the flipper button in.

The EOS switch Capacitor.System 11 EOS switches use a
2.2 mfd 250 volt capacitor to be used only (part number 5045-12095-00)
with the parallel wound FL11630 flipper coils (used on F-14 Tomcat and
later). This minimizes the high voltage electrical arc between the
contacts of the EOS switch. Games High Speed to Millionaire that use
the series wound FL23/600-30/2600 flipper coils do not need this
capacitor (it won't help save the EOS switch because the coil is wound
in series, not parallel). But on system 11 games with F11630 coils
(F-14 Tomcat and later), this capacitor should be installed.

Flipper Coil Numbers and Strength.When you get a new
game and are rebuilding the flippers, check the game manual and make
sure the proper flipper coils are installed. Often operators will
replace flipper coils with the wrong coil. Use what the manual
suggests for proper game play. Here are the relative flipper coil
strengths, from weakest to strongest:

FL11753: parallel wound, used for small flippers, like the
"Thing" flipper on Addam's Family. Requires two flipper diodes.

FL24/600-30/2600: series wound, "weak" flipper strength, and
used on Grand Lizard's upper flippers. Requires one flipper diode.
Same strength as FL11722.

FL11629: parallel wound, strongest Williams flipper. Used on
most of the newest WPC games. Requires two flipper diodes.

Convert to the Newer "Parallel Wound" Flipper
coils?Really this is a good idea. If you need to replace a
flipper coil on your older system 11 game (High Speed to Millionaire),
I would recommend converting to the newer parallel wound flipper coil
(FL11630 or FL11722 for weaker upper flippers). This way you can add
the 2.2 mfd EOS switch capacitor, and you'll get much longer life from
your EOS switch. You don't need to convert both flippers at one time
either.

The diode on a series wound FL23/600-30/2600 flipper
coil. Notice the two wire on the right lug. These are the power wires.
There are two because the power "daisy chains" to the next coil down the
line. These power wires connect to the BAND side of the diode. The EOS
switch connects to the far left lug (the ground connection), and the
middle lug. The far left lug is the "thick coil wire winding"
lug.

Left: A parallel wound FL11630 flipper coil. Note the lug on
the far right is the common lug, with both the thin and thick coil winding
wires attached. The center and the left lugs connect to the EOS switch
(the wires going up). The two outside lugs are the power and return wires,
with the gray power wire going to the right lug (the lug with the diode
bands closest).Right: The EOS switch and the 2.2 mfd 250 volt
non-polarized capacitor that attaches to it.

Here are the instructions to convert an older FL23/600-30/2600 or
FL24/600-30/2600 flipper coil to the new parallel wound FL11630 or
FL11722 flipper coil (and add the 2.2 mfd EOS switch cap). Or here's
how to just install another FL11630 or FL11722 coil in your game.

Turn the game off and remove the FL23/600-30/2600 or
FL24/600-30/2600 coil from the game. You will have to unbolt the
coil stop to do this.

Install the new FL11630 or FL11722 coil. It's best to install
the coil with the solder lugs furthest away from the coil stop (but
the flipper wires aren't always long enough to do this).

Note the lug on the FL11630 or FL11722 coil with BOTH the thin
and thick coil winding wires attached to it. The Band of the diodes
should both be towards this lug.

Hook up the EOS switch wires to the center lug and outside
non-banded diode lug, with the thin coil winding wire attached.

Hook up the power wires to the two outside coil lugs. And yes it
DOES matter which wire goes to which lug! The main power wire should
attach to the outside lug closest to the diode bands (the common lug
with both the thin and thick coil winding wires attached). This
should be the same wire you removed from the old coil lug with the
banded diode attached.

If you get the two outside lug power wires reversed, a 50 volt
solenoid fuse will blow, and the flipper buttons will not control the
flipper coils! Instead they will do something weird like turn the
flash bulbs on. Just reverse the wires and install a new fuse, and
you're all set to go.

The CPU Board Flipper Relay K1.The flippers are only
enabled during game play and in diagnostic mode. The flipper enable
relay is what turns the ground off and on connected to the flipper
coils. The flipper enable relay is located on the CPU board at K1, and
is a 4P, 40 ohm, 6 volt relay. When you enter diagnostic mode, you
should hear the flipper relay K1 click on (activating the flipper
buttons).

EOS Switch Maitainence.The EOS switches on all system 11
games do need periodic maintenance. Since they are high voltage
switches, there is some electrical arcing. The arcing is much more of
a problem on High Speed to Millionaire games with the series wound
FL23/600-30/2600 flipper coils. Excessive EOS switch arcing will cause
the switch contacts to pit and burn, and cause some resistance. As the
resistance increases, more arcing occurs (which causes even more
resistance). Eventually, bad EOS switches will make the flippers very
weak. They must be filed clean with a small point file periodically.
The switch contacts are made of Tungsten.

Adjusting the EOS switch.The EOS switch should be
adjusted (after filing it clean) so there is about 1/8" gap when the
flipper is at full extension. Any less than that and you are asking
for trouble. Any more than that and you are scraficing flipper power.

Shorting the Flipper EOS switch to the Lane Change
switch.Williams has a feature called "lane change" in many of
their games. This allows the player to change the lit lanes using the
cabinet flipper buttons. Prior to Banzai Run, this is done by doubling
up a second switch on the flipper EOS switches. The EOS switches are a
+50 volt switch. The lane change switch is a +5 logic switch connected
to the switch matrix. These two switches are insulated from each other
by a small nylon "triangle" activator. But if these two switches
touch, the switch matrix will burn (as described above).

When adjusting or cleaning the flipper EOS switches or lane change
switches, make sure the game is turned OFF. This will prevent shorting
these two switches together. Also, do not clean the smaller lane
change switch with anything other than a business card.

Lane Change on games with Interconnect boards.When the
interconnect board was introduced on Banzai Run, Williams stopped
using a doubled up switch on the flipper EOS switches for the lane
change. Instead, circuitry was added on the interconnect board using a
MOC3010 opto coupler. If you have problems with the lane change on
these games, replacing the small 8 pin MOC3010 opto couplers will
usually fix the problem.

Flipper Rebuild Kits.Williams sells a flipper rebuild
kit that contain all the parts you would need to rebuild two flippers.
It includes parts like the entire right and left flipper pawl and
plunger/link assemblies, coil sleeves, coil stops, EOS switches, EOS
switch capacitors (for the non-fliptronics kits), and other parts. At
$20 a kit (to repair two flippers), it's a pretty decent deal because
it's all the parts you'll need in one kit. But you can save some money
if you just replace the parts that are worn (the plunger/link, link
bushing, coil sleeves and usually the coil stops). For newer style WPC
fliptronics flippers, the kit's part number is A-13524-8. For system
11 flippers, it's part number A-13524-1. The genuine Williams kits
come in a cute plastic clamshell container.

Left: Flipper assembly with the coil stop (and
coil) removed.Right: The coil stop. Notice the mushroomed
head on the top example. Below that is a re-worked coil stop (using a
file). It is recommended replacing the coil stop rather than re-working
it.

Measuring the coil stop with a dial caliper. The thickness of
a new coil stop is .440 inches.After re-working, if yours is .425
inches or less,replace it.

Rebuilding Flippers: Removing the Coil Stop.First, use
your allen wrench and remove the two 10-32 x 3/8" bolts that hold the
coil stop in place. This will release the coil from the assembly. Move
the coil to the side for now.

Examine the coil stop. Often, the coil stop will have a
"mushroomed" head. This happens from the coil plunger slamming into
the coil stop. If this is the case, replace the coil stop. In a pinch,
you can re-work the coil stop and file the mushroomed head flat and
bevel the edge. The problem with this is plunger travel length
increases. If excessive, the plunger link will now slam into the top
coil bracket, destroying it. Also the increase in plunger travel can
cause the flipper pawl to hang on the EOS switch (leaving the flipper
in the up position). A new coil stop is .440 inches thick. If your
coil stop, after filing, is less than .425 inches thick, you should
replace it. Less than .425, and you'll have problems with the flipper
pawl hanging on the EOS switch. Coil stops are less than $1 each. If
in doubt, just replace it!

The flipper assembly with the pawlassembly removed.
The flipper shaft canbe seen extending through the playfield,and
through the nylon flipper bushing.

Removing the Flipper Pawl Assembly.Use your allen
wrench and an open wrench, loosen (but don't remove) the bolt that
clamps the pawl assembly to the flipper shaft. From the playfield
side, turn and pull the flipper while holding the pawl assembly until
the flipper can be pulled from the playfield. The pawl assembly can
then be removed from under the playfield.

Worn Coil Bracket?If the game was played so much that
the coil sleeve wore out (thanks in part to a worn plunger link), the
plunger could then come in contact with the coil bracket. This would
elongate the bracket's hole. Also, if the coil stop was filed (to
removed a mushroomed head) and plunger travel increased, this could
ruin the coil bracket too. In either case, the coil bracket will need
to be replaced.

Replace the Flipper Bushing?The flipper bushing is a
nylon part that the flipper shaft passes through. Unless it is
cracked, or the flipper was very weak, or the game has more than
30,000 plays, it may not be necessary to replace this part. It's
pretty easy to tell if it needs replacing. With the flipper pawl
removed from the flipper shaft, wiggle the flipper on the playfields,
side to side. There should be some play, but not excessive play.

When replacing the flipper bushing, remove the entire flipper
bracket from under the playfield. This allows access to the three 6-32
x 3/8" bolts and nuts that hold the bushing to the bracket. These
bolts have nuts on the bottom side of the flipper bracket, which can't
be accessed with the bracket in place.

Left: Note the flipper link's hole has elongated.
Also, the black heat shrink tubing on the pawl is very worn from
activating the EOS switch. Although it doesn't look it, the flipper link
spacer bushing (lower left) is also worn.Right: Note the
plunger tip has mushroomed, and there is considerable plunger
pitting.

Rebuilding the Pawl.The flipper pawl assembly can now
be rebuilt (if you buy a whole new flipper pawl assembly with a new
plunger/link for about $10, skip this section). Remove the allen bolt
that holds the flipper plunger/link to the pawl. The plunger/link can
now be removed (you may need to use a screwdriver to spread the pawl
assembly slightly to release the plunger/link).

Top: New style, fatter and more substantial flipper
link.Middle: Old style, thinner flipper link; the preferred
version for the newer style return spring set up. Since it's not as
thick, it doesn't hang up inside the flipper pawl assembly as easily.
It's also a more versatile link, and can be used in most Williams (and
DataEast!) games from the mid-1980's and forward.Bottom: Old
style, chewed up link from a flipper plunger return spring. This is why
Williams went to the newer style (top) plunger link. The plunger return
spring just hacks away at the link.

Inspect the flipper link spacer bushing, which should be
inside the flipper link's hole. Brand new bushings have an outside
diameter of .310 inches, and an inside diameter of .090 inches. If you
have a dial caliper, measure yours. If even .003" less than these
values, replace this bushing. If in doubt, just replace it.

Replace the flipper plunger and link. A new plunger/link can be
bought for $1.50. (rebuilding the plunger is hardly worth it. Spend
the $1.50 and get a new plunger/link. If rebuilding the plunger/link
is your only option, here's what to do: grind and bevel the plunger
tip to remove the mushroom. Using a 1/8" metal punch, remove the roll
pin that holds the link in place. Install a new link, and hammer the
roll pin back in place. Make sure the new link moves freely.)

Install the plunger/link and a flipper link spacer bushing.
Remember the allen bolt that holds this is place goes through the pawl
assembly with the nut on the same side as the pawl (see pictures).

Replacing the Pawl Heat Shrink Tubing.The flipper
pawl's job is to activate the EOS switch at the flippers' end of
stroke. This metal pawl tab is factory coated with heat shrink tubing
to prevent wear to the EOS switch. When the coating is worn,
metal-to-metal contact (pawl to EOS switch) occurs. This will shred
the EOS switch blade. When the EOS switch blade frays, it can hang-up
on the flipper pawl. This will cause the flipper to stick in the up
position (regardless of the condition of the return spring).

The heat shrink tubing also provides insulation between the metal
flipper pawl and the EOS switch. This is especially important because
the EOS switch is a high voltage switch. Worn or missing heat shrink
tubing on these games can cause all sorts of strange game behavior.

New pawl heat shrink tubing should always be installed when
rebuilding the flippers. Cut the old tubing off using a razor blade.
Cut a 1/2" length of new 1/4" heat shrink tubing. Push it over the
pawl, and use a heat gun or hair drier to shrink the tubing in place.
Trim with a razor blade as needed.

Installing the flipper pawl and flippercoil. Note the
use of the white plasticflipper "tool" to get the spacing
correct.

Flipper Coil Types.Often, operators will replace a
flipper coil with the wrong type. This happens quite often. You should
verify in the manual that your particular game has the correct flipper
coil installed.

Re-installing the Flipper Pawl Assembly and Flipper
Coil.After the flipper pawl assembly is rebuilt (or replaced),
reinstall it. Put the plunger through the coil bracket. Make sure the
pawl is down (toward the playfield). Push the flipper shaft through
the flipper bushing and into the pawl assembly. Do not tighten yet.

Put a new coil sleeve in the flipper coil. If you can't get the old
coil sleeve out of the coil, replace the entire coil (it has been heat
damaged otherwise the coil sleeve would easily slide out). The coil
sleeve should be installed from the non-terminal end of the coil, and
extend through the coil at the terminal end about 1/8".

Put the flipper coil in place, the coil end with the wire
terminals goes closest to the flipper pawl. Note the nylon "tab" that
is molded into the nylon terminal portion of the coil. This tab will
fit into a notch in the coil bracket. The extended part of the coil
sleeve will go through this coil bracket too. Install the coil stop
and its two allen bolts.

Changing to the New Style Flipper Return
Spring.Williams changed flipper return spring styles in 1992.
So on system 11 games, there's a cone-shaped flipper return spring
that goes over the flipper plunger. The problem with this set up was
it chewed up the flipper link, and often the spring just got weak and
broke from the constant contact with the flipper link.

To combat this problem, Williams made two changes. First they
changed the style of flipper link to be thicker, and have a more
rounded contact point. Second they stopped using a cone style return
spring. The return spring was moved outside of the plunger, where it
takes less abuse and doesn't chew up the flipper link.

Left: Here the flipper plunger spring has gone soft, and
won't return the flipper back. Note how the spring is biting into the
flipper link (new style flipper links help prevent this).Right:
A conversion to the new style return spring. This involved using
Fliptronic flipper pawl parts, and drilling a 1/16" hole in the metal
bracket holding the flipper capacitor. Be careful you don't damage the
EOS capacitor when doing this modification.

To change to the new style return spring on older flippers, just
order the fliptronics style flipper pawl (the only difference is an
added spring lever). Then drill a 1/16" hole in the bracket that holds
the flipper capacitor. This hole will anchor the new style return
spring. Be careful when drilling the new hole you don't damage the EOS
capacitor. Entire flipper pawl, with plunger and link is part number
#A-15848-L (left), or -R (for right). The flipper pawl only is part
number #A-17050-L (left), or -R ( for right).

Tightening the Flipper Pawl Assembly.Now you are ready
to tighten the flipper pawl assembly to the flipper shaft. Williams
provides a white plastic spacing "tool" (that comes with every game)
which fits between the flipper bushing and the flipper pawl (see above
picture). This spacer is .030" thick (1/32"), or about the thickness
of three business cards.

Using a toothpick as a flipper alignment
tool.

On the top of the playfield, note the roll pin inserted through
the playfield, just behind the flippers. This pin is used for
alignment purposes at the factory when the playfield was first
assembled. Put a toothpick into the roll pin, and move the flipper
against it (with the rubber installed on the flipper). With the
flipper positioned correctly, lift the playfield and tighten down
(very tight!) the flipper pawl assembly's allen bolt. Remove the
flipper spacing tool and the toothpick. I wouldn't suggest trying to
push the roll pins back through the playfield for flipper alignment;
just use toothpicks. No need to possibly damage your playfield!

Both flippers in the "up" position. Notice how they look
symmetrical.

When you are finished, extend both flippers to the up position.
They should look "equal", both extending the same amount. If not, you
will need to re-align one or both of the flippers. If you didn't
replace the flipper coil stops (and instead filed them down to remove
a mushroomed head), the flippers may not line up when extended. This
happens because the plunger travel has increased from filing the coil
stop.

Cleaning and Adjusting the EOS Switch.Cleaning and
adjusting the EOS (end of stroke) switch is the last step in
rebuilding flippers. This is VERY important. The EOS switch is what
diverts power away from the high-powered side of the flipper coil. If
not adjusted correctly and the EOS switch stays closed, the flipper
coil can burn. If the EOS switch is dirty and doesn't make good
contact, the flipper will be extremely weak. Therefore it's critical
that the EOS switch be adjusted and cleaned on all system11 flippers.

Clean the EOS switch contacts with a small metal file. There should
be no pitting in the contacts when done. The EOS switch is a normally
closed switch. So adjust the non-fliptronics EOS switch so it opens
about 1/8" at the end of the flipper's stroke. If the switch is in
really bad condition, replace it.

Parts Reference.

Flipper Rebuild Kits (for two flippers). Includes all the
following parts, plus some others. Part number A-13524-8 (actually
for WPC fliptronic flippers, with the new style return sprint). The
old style cone spring style (not recommended) is part number
#A-13524-1.